Catalyst degradation determining device for straddled vehicle and straddled vehicle including same

A catalyst deterioration determining device for use in a straddled vehicle having

• an engine,
• a transmission that transmits motive power of the engine, and
• a catalyst that cleans an exhaust gas from the engine, the catalyst deterioration determining device comprising:
• a running state acquirer that acquires a plurality of running states, which include an acquired value of each of
• one of a plurality of gear ratios of the transmission,
• an intake state of the engine, and
• a rotation speed of the engine;
• a state determiner that
• stores a plurality of allowable conditions, each of which is a condition for determining work in regard to a degradation state of the catalyst to be executed and is based on a relationship among the plurality of gear ratios of the transmission, the intake state of the engine and the rotation speed of the engine, and
• determines whether the plurality of running states acquired by the running state acquirer satisfy the plurality of allowable conditions;
• and
• a determination executor that
• executes the determining work in regard to the degradation state in a case where the plurality of running states acquired by the running state acquirer satisfy the plurality of allowable conditions, and
• does not execute determining work in regard to the degradation state in a case where the plurality of running states acquired by the running state acquirer do not satisfy the plurality of allowable conditions.